Stencil recording blank and process of preparation



Dec. 29, 1953 H. R. DALTON STENCIL RECORDING BLANK AND PROCESS OF PREPARATION Filed June 17, 1947 20 W n 3'35 72 f5 2 ,0

A BC in. A 53 :3 i 3 INVENTOR BY a M Patented Dec. 29, 1953 UNITED STATES PATENT OFFICE Harold R. Dalton, Jenkintown, Pa., assignor, by inesne assignments, to Timefax Corporation, New York, N. Y., a corporation of New York A plication June 17, 1947, Serial No. 755,263

(01. lei-128.2)

17 Claims. 1

This invention relates to record blanks and more especially to blanks which are to be used as stencils for duplication purposes.

In the art of making stencil sheets, it has been the conventional practice to employ a sheet of initially porous paper such as Yoshino paper upon which is deposited a coating material that is removable by impact pressure of a type face or the like. The exposed area of the paper is thus porous to any suitable duplicating ink. One of the great disadvantages of these conventional stencil sheets is their fragility, which considerably limits the number or times the stencil can be used for duplicating purposes. Furthermore such sheets are not usable for recording electrical signals such as telefacsimile signals, telegraph signals, and the like. I

Accordingly, one of the principal objects of this invention is to provide a stencil sheet which is free from the above=noted, and other, disadvantages of the conventional stencil sheets made from porouspaper and the like.

Another object is to provide a stencil sheet wherein the sheet stock is initially non-porous but is rendered porous only in localized areas at which the recordings are made.

Another object is toprovide a stencil sheet which does not require the usual impact removable coating but which on the other hand is responsive to electrical signals to be recorded.

A further object is to provide a stencil sheet which is formed of a plastic such as a film-forming resin or elastomer.

A still further object is to provide a recording blank which is particularly useful in recording electric signalssuch for example as facsimile signals,- and which blank can be used directly as a stencil sheet for duplication purposes.

A feature of the invention relates to a recording blank in the form of a plastic film or sheet of a polyvinylresin or mixture of such resins. 7

Anotherfeature relates to a facsimile recording blank in the form of a supporting backing to which is fastened, iii a readily strippable' manner, a coating or layer of a film-forming resinor elas tomer. This coating or layer is normally nonporous but is rendered porous in localized areas, in response to electric signals representing the facsimile recorded subject matter. Asa result, the blank can be used a great number of times as a stencil to reproduce the record by any wellknown process such as mimeo'graph, hectograph, or even by photography by using the stencil in the manner of a photographic negative.-

A further ie'ature relates to a novel facsimile recording blank comprising a supporting base of paper, cardboard, or some similar inexpensive material, on which is deposited a continuous layer or coating of a film-forming resin or elastomer, which incorporates conductive particles so that when the blank is subjected to the action of electric potentials from a recording stylus or the like, the coating is correspondingly perforated. As a result of this perforation, there is produced a permanent copy on the face of the supporting member, and when the coating is stripped from the supporting member, it is a complete stencil of the recording.

A further feature relates to an improved facsimile recording blank consisting of a plurality of bonded layers of film-forming resin or plastic, the various layers having incorporated therein conductive particles such as carbon black and the like, to render the blank suitable for facsimile recording purposes.

A further feature relates to a novel method of preparing and making stenciled record sheets for duplication purposes.

A still further feature relates to the novel combination and composition of parts which cooperate to provide an improved facsimile recorded stencil. v

Other features and advantages not particularly enumerated, will be apparent after a consideration of the following detailed descriptions and the appended claims.

In the drawing which represents, by way of example, certain preferred forms of the invention,

Fig. 1 is a perspective view of the blank according to the invention and before the stenciling operation.

Fig. 2 shows the blank of Fig. 1 after it has been stenciled.

Fig. 3 is a magnified cross-sectional view of Fig. 2.

Fig. 4 shows the blank of Fig. 2 in the process of stripping the stenciled film from its supporting backing.

Fig. 5 is a schematic diagram of a typical manher of preparing the stencil by a facsimile process.

Fig. 6 is a modification of the blank of Fig. 2.

Fig. '7 is a magnified cross-sectional view or" the blank of Fig. 6.

Fig. 8 is a further modification of Fig. 2.

Fig. 9 is a diagrammatic view of one typical method of measuring the resistance of a film prepared according to the invention.

Referring to Fig. the stencil according to the invention comprises one or more integrally bonded layers of a film-forming resin, plastic, or elastomer 10, into the body of which is incorporated a predetermined amount of powdered conducting material such as carbon black for the purpose of controlling the electric conduc tivity of the layer ID. This layer II when prepared according to the examples described hereinbelow, is substantially non-porous with a relatively smooth continuous surface as distinguished from porous paper, fabric, or the like. The layer I nevertheless possesses a great amount of pliability enabling it to be readily stripped from a suitable supporting backing ll of paper, cardboard, or similar inexpensive material.-

The backing ll merely acts as a carrier or support for the layer In and it should be of such a character as to allow the layer Ill to be easily stripped or removed bodily from the backing I! after the recording has taken place. Many kinds of paper, cloth, or similar material may be used for the backing l I. For example, almost any smooth surfaced paper such as those known as high-finish papers, machine-glazed papers, or even certain coated papers, are satisfactory. The kind of pulp used for making the paper backing H is not important, and either sulfite or kraft pulps are preferred. Also, it is not necessary to smooth both faces of the paper, and preferably only the face in contact with layer if: need be smooth-surfaced. If the paper H is a coated paper having a, pigmented coating with a binder for the pigment, a binder should be chosen which will not be affected by the subsequent applica-= tion of the stencil coating m. such binders, may be mentioned starch, casein, polyvinyl alcohol, and the like. If desired, the backing H may take the form of a cloth having a suitable finish comparable to the papers described above. In other words, the backing cr carrier ll may be any sheet material which will easily release the stencil coating it after a re"- ord has been made on it. This releasing or stripping of the coating it) can be eifected either by a simple mechanical stripping action, or by dissolving the backing H by a suitable chemical, or the backing II can be softened in any suitable manner to facilitate the stripping operation. The thickness of the backing H is not critical, its thickness depending upon the particular requirements to be met. For example, its thickness may vary from approximately 0.001 inch to approximately 0.008 inch. The strip layer H] is, in accordance with the invention, prepared from any one of a number of pliable film-forming resins or elastomers, preferably from polyvinyl resins such as vinyl chloride-vinyl acetate copolymers, vinyl chloride polymers, vinylidine chloride copolymers,' styrene polymers, elastomers, etc. It is to be understood, therefore, that in the ensuing descriptions and examples, Wherever a polyvinyl resin of any one type is mentioned, any one of the large number of polyvinyl resins of film-forming character can be substituted with slight modification to'give satisfactory results.

The invention is not limited to any particular manner of depositing the stencil strip it on the backing M. It may be applied by casting, coating, spraying, dipping, or brushing. Furthermore, the invention is not limited to the application of a single stencil coating, and if desired, one or more layers of the above-mentioned film-forming resins may be applied. The film i0 is, in accordance with the invention, ar-

As examples of 4 ranged to be perforated in localized areas in response to the application of electric potentials to these areas, for example, by means of a recording stylus as will be described hereinbelow in connection With Fig. 5. The electrical conductivity of the stencil strip Hi can be regulated by incorporating into the layer material a suitable quantity of colloidal carbon or conducting carbon. As examples of such conducting carbons may be mentioned acetylene black, thermal decomposition carbons, carbon blacks, etc. The selection of the right colloidal carbon or carbon black is a matter of choice, although nearly all carbon blacks of good electrical conductivity can be used and substituted for those given in the ensuing examples.

In the case of electrical recording by means of a stylus, improved results may be obtained if the stencil strip id is formed of more than one layer or film of polyvinyl resin containing different types of conducting carbon, or carbon blacks of widely different electrical resistance, so as to carry the stylus currents more efiectively. Thus as shown in Fig. 8, if the backing i l is of non-conductive paper; or cloth, the stencil strip it can be made of two superposed coatings Hid, Nib, of the polyvinyl resinous materials in which the coating adjacent to the backing H should be designed to have the higher electrical conductivity in order to carry the recording current with as little loss in energy as possible to the grounding strip or drum of the facsimile receiver. Preferably, the film-forming coatings ifla, itb, are provided with a whitish masking coating 26 as described hereinbelow. Where the stencil strip it is made from two such superposed coatings, special methods for keeping the coatings from intermingling may be employed, for example, a polyvinyl resin may be selected for the first coating so that the solvent used for the polyvinyl resin of the second coating does not have any effect upon the first coating. Instead of using different solvents for the two coatings,they may be cast as separate superposed films, the first film being cast and rapidly dried before superposing on it the second film. It will be understood of course that the invention is not limited to a stencil strip iii of different or graduated electrical resistance transversely thereof, and a single unitary film of uniform transverse resistance may be employed.

If the backing ii has good electrical conducting properties, for example if it is in the form of aluminum foil, or electrical conducting paper, a correspondingly lower electrical resistance may be employed in the stencil strip iii.

The incorporation of the conducting material in the strip iii in addition to enabling it to be used for stylus recording, also has the advantage that during the recording a duplicate transfer record in the form of deposited carbon is produced on the surface of backing ll. Consequently, when the stencil strip iii has been stripped from the backing l I, as illustrated in Fig. 4, there appears on the said backing strip a permanent record of the recording. At the same time, this record is recorded in the strip It in the form of transverse minute perforations.

Referring to Fig. 5, there is shown in schematic form a typical method of perforating the blank of Fig. 1 in accordance with electric signals. Thus there is shown in the left-hand portion of Fig. 5 a conventional facsimile transmitter comprising a scanning drum l2 which is adapted to be rotated at a suitable speed by a motor [3, and also simultaneously fed longitudinally of its axis, for example by a lead screw l4 and splitnut 15. The facsimile subject matter in the form of a sheet or film i0 is wrapped around drum l2. Associated with the drum is a scanning head of any well-known construction comprising a scanning light source it and a photoelectric cell 18 for translating the shades of the successive elemental areas of subject i6 into corresponding electric signals. These si nals are then applied to modulate an audio frequency carrier from the carrier source 10 through the amplifier modulator unit 20. At the receiving station shown in the right-hand portion of Fig. 5, there is provided a scanning drum 2! which may be similar to drum i2. Drum ii is arranged to be driven in rotational and longitudinal syncronism' with drum it? by means of a motor 22 and a lead screw 23'. The recording blank such as the blank of Figs. 1 and 6 is wrapped around drum 2|, and cooperating with this blank is a recording conductive stylus 25 which is supplied with electrical energy from the receiving amplifier 25 preferably, although not necessarily, through a transformer 200. which is connected to the transmitting amplifier 20. By reason of the character of the recording blank on the drum 2|, these electric signals cause the film ii] to be perforated in localized areas corresponding to the original subject matter on the transmitting blank [6. When the recording has been completed, the blank is removed from drum 2i and the stenciled film or strip is is stripped from its backing II. This stenciled strip can then be used to duplicatethe recording by any well-known duplicating process. Because of the porous nature of the stencil only at the areas where the recording takes place, ordinary hectograph or mimeograph processes can be employed. Since the blank is only perforated at the regions where the recording takes place, its overall strength is not greatly reduced,

and therefore it may be used to produce agreat number of duplications.

Since the blank of Figs. 1 and 2 has the stencil strip la formed with carbon black incorporated therein, it normally presents a black surface.

Consequently, it is very difficult to observev the In determined by the voltages available atthe recording stylus 25. Preferably however, for practical purposes. the strip [0 with its masking coating should not exceed approximately 0.006 inch, and preferably should be between 0.001 and 0.003 inch. One of the advantages of using alternating or pulsating current to excite the stylus 24 is that the stylus does not remain continuously energized as it would be if direct-current were employed. This is of importance when it is considered that in many cases the. recorded subject matter may include one or more continuouslines. Since the recording is effected by perforating the strip l0, the presence of any such continuous lines would present a continuous tear along an appreciable length of the sheet. This might not only weaken the sheet, but it might cause buckling and interference with the.stylus-24-dur-= ing the recording process. The recording on the The overall thickness of the strip 10. with its masking coating 26 will, of course, bev

strip I0 therefore consists of a large number of minute holes or perforations which are of sufficient size to allow the passage therethrough of the ink from a copying machine. The diameter of these holes may be made to vary in accordance with the amplitude of the signal voltages applied to stylus 24.

The invention is not limited to any particular method of preparing the polyvinyl resin coating for the strip or film ID. The polyvinyl resin film may be cast from solution, organosol dispersions, lattices, emulsions, etc., or they may be formed by hot calendering or extrusion methods well-known in the art. There are given below typical examples of compositions for the strip film l0 and for the masking coating 26.

Example 1 Organosol dispersion satisfactory for producing an unsupported film ID or such a film mounted on a carrier II.

Parts by weight Vinylite Resin VYNVl (Carbide & Carbon Chemicals Corp.). (Copolymer of vinyl chloride and vinyl acetate with approximately vinyl chloride) 465.0 Dioctyl phthalate 385.0 Xylene 1500.0 Naptha thinner 1500.0 Stabilizer C-2 (Carbide & Carbon Chemicals Corp.) 5.0 Acetylene black a. 300.0

The above ingredients are placed in a ball mill and ground for approximately eighteen to twentyfour hours. This dispersion can then be cast or deposited on a suitable belt or carrier on which it may be dried and fused into a film by any methods well-known in the art. The film, after leaving the fusing oven, may be stripped from the belt or carrier if desired. If the carrier is of paper or cardboard, .it can be left thereon for use as hereinabove described. If the total percentage of solids in the above-described dispersion is insufficient to provide a film of the desired thickness, it may be necessary to deposit several films in superposed relation to attain the desired thickness. Preferably the finished film should have a surface resistance of approximately 2,000 to 5,000 ohms.

Where the film I0 is to have a masking coatingsuch as the coating 26 (Fig. 6), the following is a typical example of the composition of such masking coating. Since the strip film it contains a large percentage of carbon, it appears substantially black. Consequently, the coating 26 should preferably be whitish or at least light colored, so that when it is removed in the localized areas by the facsimile signal potentials, it produces a sharp contrasting appearance. A typical example of such a composition for the coating 26 may be as follows:

The above ingredients are milled until the zinc sulfide is thoroughly dispersed. The lacquer may be thinned to the desired consistency with ethyl acetate or other suitable thinner to give a satisfactory consistency for coating by the method chosen.

Instead of forming the film from a dispersion, it can be prepared by a calendering or extruding process, in which event its composition may be as follows:

Example 3 For the preparation of a film by the calendering or extrusion process, the following formulation may be employed:

Parts by weight Vinylite Resin VYNS (average molecular weight, 16,000) (Carbide 8: Carbon Chem.

Corp.) (Copolymer of vinyl chloride and vinyl acetate with approximately 90% vinyl chloride) 150.0 2047 Black (Godfrey L. Cabot Inc.) 150.0 Dioctyl phthalate 50.0 Tricresyl phosphate 50.0 Stabilizer C-2 (Carbide & Carbon Chemicals Corp.) 6.0

Example 4 (A) First conducting film formed on belt or carrier.

Parts by weight Vinylite Resin VYHI-l (Carbide 8; Carbon Chem. Corp). (Copolymer of Vinyl chloride and vinyl acetate with approximately 85% vinyl chloride. Average molecular weight, 10,000) 300.0 Acetylene black 150.0 Dioctyl phthalate 50.0

Methyl ethyl ketone 1200.0 Stabilizer C-2 2.0

The resin is dissolved in the solvent and acetylene black dispersed or ground as by means of a roll, colloid or ball mill, etc.

The above-described conducting film of Example 4(A) can be applied by any suitable means to a belt or carrier which may be of paper or cardboard until the coating has a dry thickness of approximately 0.0005 inch to 0.0015 inch, with a surface electric resistance in the film of approximately 500 to 2,000 ohms.

Example 4 (B) Second conducting film applied over (A) on belt or carrier to form a single film having a resistance gradient.

Parts by weight Vinylite Resin VYHH (see above for properties of this resin) 300.0 Dixie Black (United Carbon C0.) 90.0 Dioctyl phthalate 50.0

Methyl ethyl ketone 1200.0 Stabilizer C-2 2.0

In the above formulations (A) and (B) vinylidene chloride, acrylonitrile copolymer (Dow Saran F-120, 200 vis.) may be substituted for Vinylite resin VYHH. The resin is dissolved in the solvent and acetylene black dispersed or ground as by means of a roll, colloid or ball mill, etc. The coating formed by Examples 4(A) and 4(3) should have a dry thickness of approximately 0.0005 to 0.0015 and with a surface resistance of approximately 1,000 to 8,000 ohms. If desired, a masking coating, such as coating 26 and described as Example 2, can be applied over the combined conducting films of Examples 4(A) and 4(3) Preferably, the total thickness of the three coatings of Examples 4(A), 4(B) and the masking coating, should not exceed 0.005 inch and should preferably be between 0.001 and 0.003 inch.

There is shown in Fig. 9 an example of a preferred method of measuring the resistance of the films referred to in Examples 1, 2, 3 and 4 above. A strip of the film material, for example nine centimeters long by three centimeters wide, has clamped thereto a pair of Wire electrodes 2'5, 23 each one centimeter in length and spaced apart by one centimeter at the central region of the strip, the electrodes being connected to a suitable resistance measuring instrument such for example as a Wheatstone bridge.

While certain particular compositions have been mentioned herein, it will be understood that various changes and modifications may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. An electro-sensitive blank for conversion to a perforated stencil in response to stylus-applied electric signals, comprising a sheet of non-porous, non-fibrous pliable plastic associated with a supporting backing, said sheet being of film-forming polyvinyl resin to be perforated through its complete thickness by said signals and having electrically conductive carbon dispersed non-uniformly through the sheet thickness with the resistance increasing in a direction from the backing through the sheet thickness to make it an electric conductor and to impart uniform sensitivity of transverse perforatability over its entire extent for a given intensity of a stylus-applied electric signal, said sheet having a surface resistance of between 500 and 9000 ohms when measured between contacts 1 centimeter long engaging the sheet and spaced apart 1 centimeter.

2. A new article of manufacture for the production of a non-fibrous stencil in response to stylus-applied electric signals, comprising a normally non-porous and non-fibrous sheet for association with a supporting backing member, said sheet being of pliable plastic having powdered carbon dispersed non-uniformly through the sheet thickness imparting to said sheet a graduated electric conductivity transversely between its opposite faces, which conductivity decreases in a direction from the said backing member through the sheet thickness.

3. An electro-sensitive blank specially prepared for conversion to a perforated non-fibrous stencil in response to stylus-applied electric recording signals, comprising a sheet associated with a supporting backing, said sheet being of pliable plastic formed of at least two intimately bonded layers each of a non-porous, non-fibrous filmforming resin and each layer having incorporated therein electrically conductive carbon, to provide one layer with a different electric conductivity face re from the other layer while imparting uniform sensitivity of transverse perforatability over its entire extent for a given intensity of a stylusapplied electric signal, the layer Which is closer to the said backing during recording being of higher conductivity than the next adjacent layer.

l. An electro-sensitive blank for forming a perforated non-fibrous stencil, comprising a backing member, a first electrically conductive film of non-fibrous pliable plastic which is directly coated on to the surface of said backing without any sep arate intervening adhesive and which has substantially negligible interpenetration with the said surface so as to be separably adherent to said backing member with low adhesive affinity, and a second electrically conductive film of nonfibrous pliable plastic of lower conductivity than the first film and superposed on said first film and bonded thereto to form a unitary layer which is readily and integrally peelable as a unit from said backing while in a dry condition.

5. An electro-sensitive blank according to claim 4 in which at least one of said films is constituted of film forming resin or vinyl chloride polymer.

6. An electro-sensitive blank according to claim 4 in which at least one of said films is of a filmforming polyvinyl resin.

7. An electro-sensitive blank according to claim 4 in which at least one of said plastic films is of a film-forming resin of vinylidine chloride polymer.

8. An electro-sensitive blank according to claim 4 in which at least one of said films is of vinyl chloride-acetate co-polymer.

9. An electro-sensitive blank according to claim 4 in which said films have incorporated therein 'difierent types of electrically conductive powdered carbon to impart the respectively different conductivities to said films.

10. An electrc-sensitive blank specially prepared for conversion to a stencil by stylus-applied electric recording signals, comprising a paper backing, pliable film-forming resin material coated on to the surface of said backing, said material having a graduated electrical resistance through its thickness to facilitate the perforation thereof in minute localized areas through said thickness in response to said signals, said 1 sistance increasing towards the sur- '1 from said backing.

11. An electro-sensitive blank specially prepared for conversion to a perforated stencil by stylus-applied electric recording signals, comprising a smooth surfaced backing member, a first electrically conductive film of pliable plastic which is separably adherent to said smooth surface with low adhesive aifinity and without separate intervening adhesive, and a second film of electrically conductive pliable plastic superposed on said first film and forming therewith a unitary layer which is integrally peelalole as a unit from said backing while dry, the plastic film in contact with said smooth surface being by itself of higher electric conductivity than the other film by itself.

12. An electro-sensitive blank specially designed for conversion to a perforated non-fibrous stencil in response to stylus-applied electrical signals, comprising in combination a sheet of pliable plastic having electrically conductive carbon dispersed non-uniformly through the sheet thickness imparting to it a uniform sensitivity of transverse perforatability in response to stylus-applied electrical signals of a given intensity, and a pliable backing having a smooth surface which is negligibly penetrated by the plastic when applied directly thereto in semiliquid state, whereby substantially negligible mechanical interlock exists between the plastic and backing and the plastic when dry is readily mechanically peelable therefrom, the said plastic having a graded conductivity throu h its thickness with the higher conductivity adjacent the backing.

is. An electro-sensitive blank for recording electric signals applied thereto, comprising a supporting backing having an outer coating which is removable localized areas in response to electric signals applied thereto, and electrically conductive material sandwiched between the backing and said outer coating, said conductive material having a low resistance stratum adjacent the backing and a high resistance stratum adjacent said outer coating.

14. An electro-sensitive recording blank comprising paper base having a top coating which is removable in localized areas in response to applied electric signals to make the record, and electrically conductive material sandwiched between the base and the top coating, said conductive material having greater resistance adjacent the top coating than its resistance adjacent the base, said top coating and said conductive material being of contrasting colors.

15. An electro-sensitive recording blank, comprising a paper base, a first electrically-conductive coating on said base having a carbon filler to impart to said first coating a predetermined electrical resistance, and another electricallyconductive coating on the first coating and having incorporated therein carbon to impart thereto an electrical resistance which is higher than the electrical resistance of the first coating, and a top contrasting coating on said other electrically conductive coating and adapted to be removed in response to electric potentials impressed thereon.

16. The method of making an electro-sensitive recording blank for recording stylus-applied electric signals, which comprises applying to a non-conducting backing support an electrically conductive material having successive strata of different predetermined electric conductivity, and then applying to said material a masking coating of contrasting color and which is removable in localized areas in response to stylus-applied electric signals to expose said material thereat, said backing and said material and said masking coating being bonded to form a unitary composite blank, said conductive material being applied in successive stages to the backing, and the stratum of said material adjacent said masking coating having incorporated therein conductive carbon imparting to said stratum adiacent said masking coating a higher electrical resistance than the stratum adjacent the backing.

17. An electro-sensitive blank especially prepared for recording stylus-applied electric recording signals, comprising a pliable smooth surface backing member, a first electrically conductive film of pliable plastic containing carbon which is separably adherent to the smooth surface of said backing member with low adhesive afiinity and without separate intervening adhesive, and a second film of electrically conductive pliable plastic containing carbon superimposed on said first film and forming therewith a unitary layer which is integrally peelable as a unit from said backing when dry, the plastic film in contact with said smooth surface being by itself of higher electric conductivity than the other film by itself.

HAROLD R. DALTON.

References Cited in the file of this patent UNITED STATES PATENTS Number Number 12 Name Date Eddison Apr. 22, 1941 Gaut et a1. Sept. 23, 1941 Spooner May 12, 1942 Finch Feb. 16, 1943 Francis July 18, 1944 Smith Nov. 21, 1944 Baczewski Sept. 25, 1945 Dalton Apr. 23, 1946 Kline Aug. 19, 1947 Meigs Mar. 14, 1950 

